No audio when monitoring DTXPLORER

Greetings,
 
I am the proud new owner of a Yamaha DTXPLORER electronic drum kit. I have routed the midi out to the midi input of my M-Audio Delta 1010LT and am trying to record a drum track.
 
Like others on this forum, I quickly discovered that the kick and snare notes did not map to any instruments on the Session Drummer 3 track I have armed.
 
I have subsequently created a drump map that correctly maps all the DTXPLORER notes to their equivalent notes on the Session Drummer 3 synth. (The DTXPLORER does not allow you to change the midi channel or notes).
 
When I arm my midi drum track and strike pads on the DTXPLORER I get no sounds in Sonar. However, if I hit record and play the DTXPLORER it is in fact recording notes from the drum kit and will play when I play the track back.
 
My midi track output is routed to the drum map which is of course routing the notes to the Session Drummer 3 soft synth.
 
The soft synth is routed to an instrument bus which is routed to my Main output bus.
 
I have of course ensured that the Input Echo button is toggled on for the midi track.
 
If I route the midi track's output directly to the Session Drummer 3 soft synth I get instant gratification when playing the DTXPLORER (sans kick and snare). However, as soon as I route the midi output to the drum map I created I get no input monitoring at all.
 
Any ideas on what I could be doing wrong?
 
Thanks,
 
Greg.

For those lurking, the 8.5.2 patch did indeed fix the problem.